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Topic: Fregat Master Thread (Read 51384 times)

In the current printed issue of the French aerospace magazine "Air & Cosmos" there is a small article on an upgrade of the FREGAT for dual-launching the Galileo spacecraft with the Sojuz launcher. According to that article, the new version will include the following changes:

M1005 Mars ExpressOne of initial batch of five; two upgraded lithium batteries 9ER14PS-20, 60 Ah each after 0·5 year storage. Used only one attitude control system (ACS) hydrazine tank (-Z axis of Fregat) overfilling it with 11 kg of additional fuel, while the other ACS tank (+Z axis of Fregat) was kept empty, with all hydraulic pipelines re-moved to compensate for Mars Express centre of gravity. For the mission about 20 kg of hydrazine are required only, while each tank has a capacity of 40 kg. The cover material of the Fregat equipment bay was changed from Al-Mg alloy (AMG6) to Mg alloy (Mg-1), with the resulting mass saving of 5 kg. One of the two independent tracking systems of Fregat was removed and for most of the future flights, leaving the one certified for the range of 10,000 km. A satellite navigation unit (SNS) capable of receiving signals from the GPS and GLONASS was installed on the Fregat. The navigation data will go directly to the telemetry system, but is not used in the flight control loop. [News from Moscow № 22/2002]

I should mention here that Fregat-SB is not just a Fregat with an extra fuel tank, but rather that the "Fregat" part of the stage is a Fregat-M, which contains small additional propellant tanks affixed to the main tanks, like giant pimples or warts. I don't know if the "M" variant has upgraded avionics. I believe that the "pimple" tanks contain about a ton of additional propellant when they are all added together.

The "MU" "MT" variant of Fregat is in the works, this has similar "pimple" tanks, but they are larger.

First off, drawings of the 3 variants of Fregat, showing the small and large pimple tanks. Apparently, its possible to fit any of the 3 variants with the large SB drop tank.

The "dry" mass of Fregat for the 3 variants are: 930 kg, 960 kg, and 1050 kg, which means that the small pimple tanks hold in the aggregate 500kg of prop but have a mass of only 30 kg, whereas the large pimple tanks hold 1850 kg with a dry mass of 80 kg.

Again, the three variants of Fregat are the standard, Fregat M and Fregat MU MT.

The "standard" Fregat, without the pimple tanks, has had some modifications since its first flight in the early 2000s.

First off, there has been an extensive program to reduce the dry mass of the stage, in 3 stages.

The base Fregat had a dry mass of 1100 kg, reduced to 980 kg in 2005, and now to 930 kg (not counting pimple tanks). This was largely accomplished by modernizing the electronics. The Bizer-3 flight computer was updated to Bizer-6, and the telemetry unit was updated from BR9-TsK-1 to BR91-TsK-M4. Also, lighter aluminum alloys were used in construction of Fregat.

Lastly, the specific impulse of the engine was increased from 327 to 331 seconds by a 200 mm extension of the engine nozzle. The extension is shown here:

Fregat-SB = Fregat-M plus large drop tankFregat-SBU = Fregat MT plus large drop tank. However, it should be noted that although the pimples for this version are larger than the Fregat-M pimples, they may not be exactly the same as the Fregat-MT pimples.

Fregat 2 = Fregat with 2 complete sets of tanks, its unclear whether one of the tank sets can drop off.

All of the current variants of Fregat have the upgraded electronics and other modifications mentioned above.

One other note: for the Glonass K1 launch, we don't know which version of Fregat was used. It stands to reason that a standard version was launched, because only 1 satellite was the payload, rather than the two sats per launch which is the plan for Soyuz. IF Soyuz-2 launches Glonass from Baikonur, 2 at a time, its not clear which Fregat variant would be used.

Lastly, I have never reviewed earlier Fregat payloads to see if any them used the "M" variant. I suspect that the METOP may have used the "M", but I haven't checked.

I am probably wrong, but I have always thought that Fregat might be derived from the descent stage used on the third generation Luna spacecraft (Ye-8 series). The first use might have been as the Fobos lower propulsion stage which performed the trans-Mars injection burns back in 1988.

For METOP, yes, there was a dual telemetry system as described above, but I am not sure that the dual system is used for all launches. Whether the prime telemetry system is M4 or M6, I can't say, although I do know that M6 has a mass about half that of M4, as it is a modernized version.

The same type of system is used in Soyuz and Progress, from the same factory, or at least that was the case until the new "M" iteration.

I am probably wrong, but I have always thought that Fregat might be derived from the descent stage used on the third generation Luna spacecraft (Ye-8 series). The first use might have been as the Fobos lower propulsion stage which performed the trans-Mars injection burns back in 1988.

You are not wrong, although there were some mods between 1988 and 2000.

This begs the question as to the drop tanks used on the Luna series, how do they relate to the current SB drop tank?

Compact Telemetry System BR-91TSK-M4 is used for recording and transmission of information via radio link, storing and playing media.

System provides a telemetry signal from the information content of 800, 3200, 25,600 measurements per second battery in the radio decimeter waves (D1).

Specifications:

Power supply system in the range of 23 to 32 pulsing, impulse noise and the drawdown with an amplitude of 2 V of any duration and frequency.Power transmitting device in the range of 6 W with the possibility of switching to 15 WattsMemory Capacity 8 MB of memory.

The system provides measurement of 480 digital and 120 analog parameters, except that you can connect up to 63 temperature sensors.Current consumption of the feeder chain system does not exceed 3 A.Mass of the system without cables no more than 12,5 kg.The mass of the cables is not more than 2,1 kg.

http://www.tc-irz.ru/space?Id=35&Pic=1БР-91ЦК-М6Compact Telemetry System BR-91TSK-M6 is used for recording and transmitting information about rapidly changing parameters WITH the transmission of information via radio link.

The system provides the transmission of telemetry signals from 51,200 measurements per second on an autonomous radio UHF waves (D1).Power supply system in the range of 23 to 32 pulsing, impulse noise and the drawdown with an amplitude of 2 V of any duration and frequency.Power transmitting device in the range of 6 to 15 Watts

The system provides 28 analog measurement parameters:

6 parameters with a sampling frequency of 6400 Hz; 2 parameters with a sampling frequency of 3200 Hz; 9 parameters with a sampling frequency of 400 Hz; 11 parameters with a sampling frequency of 200 Hz.

Current consumption of the feeder chain system does not exceed 2.5 A.Mass of the system without cables ranging from 6.5 to 8.6 kg.The weight of the cables in the range from 0,8 to 1,2 kg.

I don't understand which Fregat-SB this video is showing.At first, I thought it was the MDU for Fobos-Grunt, but it wasn't yet in Baikonur on 7th september 2011 (date of video publication on TVRoscosmos).

I don't understand which Fregat-SB this video is showing.At first, I thought it was the MDU for Fobos-Grunt, but it wasn't yet in Baikonur on 7th september 2011 (date of video publication on TVRoscosmos).

Caught 1031 at 1:04 so not SB, and has Soyuz interface. For next Globalstar?

“The engine chambers are not installed in a gimbal, as usual, but in the hinge, allowing its plane-parallel motion. By this way, a displacement of the thrust vector with regard to the center of mass of the upper stage, which is located very close to the engine head, is ensured. (In this specific case, the cardan joint did not provide the necessary arm to create a moment of thrust)”

Fregat-M is supposed to be a standard Fregat with avionics upgrades plus the small "pimple" tanks. However, we are now seeing standard Fregats withe the avionics upgrades, so is the "M" variant simply a standard Fregat with the pimple tanks? How much longer are we going to see the standard Fregat, or will these be produced in parallel with the "M" and "MT" variants?

“The engine chambers are not installed in a gimbal, as usual, but in the hinge, allowing its plane-parallel motion.

Thank you for translation, YzeStudent !But I don't understand this sentence. The S5.92 is able to control its pitch and its yaw. How could it be possible with only one hinge ?And I don't understand what "plane-parallel" means...

“The engine chambers are not installed in a gimbal, as usual, but in the hinge, allowing its plane-parallel motion.

Thank you for translation, YzeStudent !But I don't understand this sentence. The S5.92 is able to control its pitch and its yaw. How could it be possible with only one hinge ?And I don't understand what "plane-parallel" means...

Are you refering to a translation in a parallel plan of an engine (or a group of)? In this case the result is equivalent to gimbaling the engine vector, as the position of the engine move from the spacecraft center of gravity...

ASN has worked on Fregat in telemetry mode (i.e. its data were not used by BTsVM) since 2003. ASN first flight in normal mode (i.e. its data were used by BTsVM) was on 17 September 2009. Since that time there were 20 Fregat flights with ASN worked in normal mode. Also ASN has worked in telemetry mode on last DM-SLB flight. NPTs AP wants to use ASN in normal mode on next DM-SLB flight, but it depends on customer's permission. ASN will be installed on DM-03 too. In next DM-03 flight it will work in telemetry mode.

ASN has worked on Fregat in telemetry mode (i.e. its data were not used by BTsVM) since 2003. ASN first flight in normal mode (i.e. its data were used by BTsVM) was on 17 September 2009. Since that time there were 20 Fregat flights with ASN worked in normal mode. Also ASN has worked in telemetry mode on last DM-SLB flight. NPTs AP wants to use ASN in normal mode on next DM-SLB flight, but it depends on customer's permission. ASN will be installed on DM-03 too. In next DM-03 flight it will work in telemetry mode.

Thank you anik for these great informations !If I understand correctly, "telemetry mode" is a mode were ASN is flown only for tests ?

Last successful planetary missions launched by Fregat were Venus and Mars express , correct ? Phobos-Grunt of course wasn't too successful.For both Venus and Mars express Fregat provided a TMI/TVI burn and then separated the spacecraft - but has a Fregat in modern history actually ever successfully operated further away from earth ? For the cancelled ESA/German moon lander they planned to have Fregat to take the lander all the way to lunar orbit including the LOI burn, and then release the lander. I'm wondering how feasible that would have been.

It appears that the last two sections are for PxOs only, with a cost under or around 100 million rubles for 14С737, and under 40 million for 14С227. So, what is the difference between the two objects, and why is one so much cheaper?

It appears that the last two sections are for PxOs only, with a cost under or around 100 million rubles for 14С737, and under 40 million for 14С227. So, what is the difference between the two objects, and why is one so much cheaper?